Prior art brushrolls generally include a central spindle supported at either end by sleeve bearings mounted on the sides of the nozzle. The spindles are turned by belts tied to a vacuum cleaner motor, either directly or through one or more pulleys. Mounted on the elongated surface of the spindle is a plurality of tufts of bristles or beater bar elements projecting normally from the surface of the spindle. As the brushroll rotates, the tufts or beater bar elements brush against the surface of the carpet and loosen dirt from the fibres. The tufts or beater bar elements are generally mounted in a helical pattern on the brushroll so as to agitate the carpet seriatim as the vacuum cleaner moves over the carpet surface.
In practice, dirt and threads loosened by the brushroll can flow along the surface of the roll toward its ends into the sleeve bearings at the sides. As a result, the bearings can foul so that the brushroll cannot turn freely in response to the belt drive.
A number of thread guards have been proposed for preventing threads from fouling the brushroll bearings. These proposed thread guards include labyrinth seals which fit over the ends of the spindle in an effort to prevent threads moving outward along the spindle from reaching the bearing. In one proposed seal, a disc-like guard includes an annular flange and radial skirt directed into an annular slot in the end of the spindle so as to form a labyrinth between the guard and the slot. One drawback to this proposed seal is that the labyrinth opens axially toward the spindle, so that thread moving outwardly along the brushroll will flow naturally into the labyrinth rather than outside and past the seal. Another drawback is that threads may collect in the annular slot, so that the seal itself may foul, inhibiting the free rotation of the brushroll. Once fouled, the end assembly of the brushroll may have to be disassembled in order to reach and remove the threads collected in the slot.
Another proposed brushroll features a spindle having a cylindrical cavity on one end. A sleeve mounted on the side of the nozzle forms an annular slot directed axially inwardly into which the end of the spindle extends to form a labyrinth. As with the previous proposed seal, this proposed labyrinth seal opens axially toward the center of the spindle so that threads flowing outwardly along the spindle may work their way into the seal.